Blue Moon - The Blue Moon of 2001

Our Blue Moon Calculator says that in 2001, there is a Blue Moon in November. You may have heard or read reports which said that the Blue Moon really occurs in October, or even in December. Who is right?

Well, you can see Blue Moons in all three months, but it depends where in the world you live.

Let's start with the basic astronomical facts. The last four Full Moons in 2001 are as follows:

2 October	at	13:49 GMT
1 November	at	05:41 GMT
30 November	at	20:49 GMT
30 December	at	10:40 GMT

These dates and times have been calculated rigorously using the same methods as those employed by the United States Naval Observatory and by Her Majesty's Nautical Almanac Office. They are given in Greenwich Mean Time which is the standard time zone used by astronomers worldwide.

Notice that the second Full Moon in the list occurs just 5 hours and 41 minutes after the start of November, and the third Full Moon is just 3 hours and 11 minutes before the end of the month. In either case, changing the time zone by only a few hours changes the month in which the Full Moon falls. In Chicago and places further west, there is a Full Moon on Halloween in 2001.

Here are those four Full Moons again, but with the dates and times adjusted for several major time zones around the world. For each time zone, the two Full Moons which fall in the same calendar month are highlighted. We have ignored daylight saving time because it has no effect on the dates of the Full Moons.

City	Time zone	Full Moon 1	Full Moon 2	Full Moon 3	Full Moon 4
Places East of Greenwich
Sydney	GMT + 11 hours	October 3 00:49	November 1 16:41	December 1 07:49	December 30 21:40
Tokyo	GMT + 9 hours	October 2 22:49	November 1 14:41	December 1 05:49	December 30 19:40
Islamabad (Pakistan)	GMT + 5 hours	October 2 18:49	November 1 10:41	December 1 01:49	December 30 15:40
Moscow	GMT + 3 hours	October 2 16:49	November 1 08:41	November 30 23:49	December 30 13:40
The Greenwich Meridian
London	GMT	October 2 13:49	November 1 05:41	November 30 20:49	December 30 10:40
Places West of Greenwich
New York	GMT - 5 hours	October 2 08:49	November 1 00:41	November 30 15:49	December 30 05:40
Chicago	GMT - 6 hours	October 2 07:49	October 31 23:41	November 30 14:49	December 30 04:40
Los Angeles	GMT - 8 hours	October 2 05:49	October 31 21:41	November 30 12:49	December 30 02:40
Hawaii	GMT - 10 hours	October 2 03:49	October 31 19:41	November 30 10:49	December 30 00:40

As you can see, places in time zones between New York and Moscow see two Full Moons in November. However, if you are in Chicago's time zone, or further west, then November has only one Full Moon. Instead, there are two Full Moons in October, and the Blue Moon falls on Halloween. Likewise, if you are further east than Moscow's time zone, both October and November have only one Full Moon each, and it is December which has two.

Once in a Blue Moon

The Blue Moon of 2001